Centrifugal mill hammer with renewable wearing tip



F. J. LOUFEK CENTRIFUGAL MILL HAMMER WITH RENEWABLE WEARING TIP Filed July 23, 1947 4 Sheets-Sheet 1 INVENTOR.

a K I LouF BY M WW Sept. 18, 1951 J, LQUFEK 2,568,077

CENTRIFUGAL MILL HAMMER WITH RENEWABLE WEARING TIP Filed July 25', 1947 4 Sheets-Sheet 2 INVENTOR.

FTP/1 NKJI LouFE/r ATTOENE vs Sept. 18, 1951 F. J. LOUF'EK 2,568,077

CENTRIFUGAL MILL HAMMER WITH RENEWABLE WEARING TIP Filed July 23, 1947 4 Sheets-Sheet 5 INVENTOR. FeAA/K JI Lol/FEK AT-rozNEYs' Sept. 18, 1951 J, LOUFEK 2,568,977

CENTRIFUGAL MILL HAMMER WITH RENEWABLE WEARING TIP 4 SheetE-Sheet 4 Filed July 23, 1947 HAMMER SET our 70 TIP NEW TIP REVERSED HAMMERArJWORTEJTRA mus ATSHORTEST RADIUS MEDIUM RAD/us SHORTESTRADIUS 3/ MEo/uMRno/us v 7 LARGEST W 435 c RAD/11S I 7 I I I I I 1 y I I V & //2 s a e\ 112 b M d f J F/Rsr /R074'4770N WEAR/Ne ROTATION ROTATION H SECOND ORIGINAL Ci WEARING OWEN/M wEA ws 76 I4 1 H613 TIP REVERSED A7 HAMMER 6E1' 001' MEDll/M RAD/US To LONG RAD/us P RE VERSED AT sfloRTEsT RADIUS LONG RAD/U6 MEDIIIMIMD/ll-f 9/ LARGEST RIADIIIS l l e e e 1/2 g I I J 1 I I Fol/Em f fiamr/o/v J WEAR/"G FIFTH ROTAT/fl/V SIXTH Rom-rm/v MIG/ML 256522 WEAR/1V6 WEARING DIMENSION, l6 F TIP OF TIP /G./6 F1617 /NVENTOR FEANKJ Low-"5K ATTOZNE Ys Patented Sept. 18, 1951 CENTRIFUGAL MILL HAMMER WITH RENEWABLE WEARING TIP Frank J. Loufek, C edar Rapids, Iowa Application July 23, 1947, Serial No. 762,983

This invention relates to hammer mills for breaking stone and the like hard, fracturable materials, and more particularly to improved renewable hammers therefor. Hammer mills for stone and similar materials, as usually constructed, have a closedhousing equipped with a chute for introducingthe material to be broken. The bottom portion of the'housing, or at least a part of it, is composed of apertured grids which are usually of exceedingly hard and tough steel, such as cast manganese steel, The grid surface is cylindrical and through the housing, and axially of the cylindrical grid surface there is a rotatably mounted shaft which; in the usual construction of mill, carries spaced discs of heavy construction that are apertured to provide a mounting for through pivot pins on which a plurality of swinging hammers are mounted.

In early hammer mills it was usual practice to make the swinginghammers of one unitary casting, one end being apertured so as to journal and henceswing on the pivot pin when mounted in place, the free-end of the'hammer being, in cooperation with;the cylindrical grid, the stone breaking surface.

Both the grids and the hammers wear during service, theynormal lifebeing onlya matter of hours before turning ofthe hammers to expose a new striking surface, orreplacement is necessary, for the operating conditions are extreme. For removal and replacement the machine is usually constructed so that the hammer mounting pins could be driven out through access places in the mill housing and through holes in the shaft flywheel. of hammers-is not an easy task, for the parts tend to lime up; that is to say, during service the interstices inbearing mounting etc. become =packed with finely ground stone. Consequently,

many hours of hardwork are needed to drive out the pins and replace or turn the hammers. "Replacing'orturning the hammershas, therefore,been veryexpensive, not only in labor and parts but also in out-of-service time of the mill.

attempt has heretofore been made to reduce these: costs-by providing a hammer with a two-part body and a removable tip. While this t pe-hammerhas achieved a considerable acceptance its use'has been attended by considerable disadvantages. To disconnect the hammer tip from the two-part body portion of the hammer, it is first necessary to remove the latter from the mill so as to allow the two parts of the body portion to be separated. Consequently, it is-still necessary, when using this type hammer assembly, to drive out the hammer mounting pins through the mill housing and flywheel each time the hammers need to be turned to expose a new striking face or for renewal. This constitutes a continuing, service @051; which is not Replacement or turning 2 Claims. (Cl. 241-197) eliminated. Furthermore, when the hammer assemblies are removed, it is difficult to, remove the tips because, by the nature of the connection between tip and two-part body portion, there is considerable interstitial. space which becomes "limed up, i. e. filledwith finely powderedstone, which packs hard, and frequently defies removal. This is also a continuing service cost. a

Furthermore, thenature of the assemblyv of privously patented, removable tip hammers has necessitated removing the hammer mounting pins each time the tipis turned or the hammer replaced. v r It is an object of the present invention to provide an improved renewable tip hammer for hammer mills and more particularly to provide an improved renewable tiphammer wherein the task of turning thetips or renewing the hammer tips can be accomplished conveniently without removing the hammer mounting'pins or body portion of the hammers from themilL'and which is capable of beingmanufacturedand serviced at minimum'costs. i ,1

Other objects of the invention include the provision of a hammer assembly having only two principal parts held together by an easily remov able through bolt, and in which the two principal parts may be'separated by simple transverse sliding movement without separating the-hammer assembly from'the mill; r a Other andfurther objects of, the invention-are those inherent in the apparatus herein il1u s-, trated, described and claimed; The invention is illustrated in the drawings in which Figure 1 is a transverse section through a typical hammer mill wherein the hammers are made in accordance with the presentinvention;

Figures 2 through 5 illustrate one style of im-, proved hammer of the present invention, here: inafter'referred to as type A. Figure 2- is a-side elevational view; Fig. 3 is-a vertical-section taken in the direction of and along line 33 of Figure 2; Figure 4" is a perspective view with the parts separated so as toillustrate the manner of; assembly; and Figure 5 is a detail ofthe-righthand side plate of the assembly, as shownin Figure3;--

Figures 6 through 8 illustrate another styleof improved hammer forhammer mills of themesent invention hereinafter referred to as type B. Figure 6 is aside elevational view; Figure! is-a vertical section along. the line and in the direction of arrows l-Lof Figure 6; and Figure fi is a perspective view with the parts separated so as to illustrate the manner of assembly;

Figures 9 through 11 illustrate still another style of improved hammer for hammer mills of the present invention,hereinafter referred to as type C. Figure 9; is a side elevationalview; Figure 10 is a vertical section along the line and in the direction of arrows Ill-l8 of Figure 9; and Figure 11 is a perspective view with the parts separated so as to illustrate the manner of assembly.

Figures 12 through 17 are a series of viewsv showing the manner in which the tips are reversed and the hammers set down through successive steps so as to maintain grindingeffi'ciency and utilize all of the hammer tip material.

Throughout the drawings, corresponding numerals refer to the same parts.

Referring to the drawings, particularly Figure 1, there is illustrated a hammer mill particularly designed for crushing hard materials, such as stone, cement, rock, and the like. Figure l is representative of hammer mills of this type and consists of a sub-frame l having an upper surface internal and external flange H on which the crusher assembly is mounted. The crusher cons-ists of a heavy cast or weldedstructure having a base plate I2 and upwardly extending walls l4 and I5. Between the base plate l2 at the left side and the internal bracing frame member Hi there is a pocket I! intowhich tramp iron is tossedduring the operation of the mill, and this is covered by a clean-out door It. The sub-frame l0 also serves as a support for a cylindrical milling grid generally designated 20 which is usually cast in sections and is of exceedingly hard and tough material, such as manganese steel. The

grid has a cylindrical inner surface 2| which is apertured so as to-form a screen or grid through which the pulverized material 22 falls during the operation-of the mill. The grid 20 may be composed of several-parts suitably supported on the sub-frame Ill. The exactconstruction of the grid forms no part of the present invention. Within the-wall portion |4=there is, in the illustrated mill, a plate 24 which ishinged at 25 and arranged for adjustable movementby virtue of the adjusting bolt 26. The hinge plate 24 is faced with a cast, hard, tough plate 21 having an irregular-grinding surface 33.- The upper portionof the mill is closed as at 28 and 29. The frame members |'5-', I 6 and 2-9 serve to support a minute. chute shown-under the bracket 30 through which the large size material which is tobe pulverized is fed downwardly in the direction of the arrow 3|.

The exact structure of the mill is varied considerably, depending upon the particular design features stressed-by various manufacturers, but all the mills of this character have in common the idea of using a reticulated cylindrical grinding surface, here represented by the grid 28, and a rotatable hammer assembly, here generally designated 31. The rotatable hammer assembly is mounted upon the shaft" 32 which is suitably journaled in the end plates of the mill and driven from an adequate power'source. customarily, the shaft-32 has on it a heavy flywheel (or flywheels) exteriorly of the frame at one (or both) of the ends of the mill to which the power drive is applied-in any suitablemanner. Within the mill, the shaft 32 is provided with a plurality of spaced discs 34 which are keyed onto the shaft at 35. The discs are provided with a plurality of spaced apertures, viz. 36A, 36B and 36C usually on radii which are spaced at equal angular intervals around the discs. In some mills the distance from the center of the shaft 32 to the center of the holes 35A, 36B-and 360 is varied slightly so as to vary the position at which the hammers are pivoted with reference to the main shaft 32, while in other mills all' of the holes 36A, 36B and 36C are at equal distance from the center of the shaft, the plurality of holes being provided in such instances only to allow shifting of the hammer anchor pins 38 when Wear occurs. In the illustrated embodiment the distance of the holes from the center of the shaft is varied slightly. Thus, holes 36A have the shortest radius from the center of shaft 32 and are used when the hammers are new and of maximum length, Figures 1 and 12-17. Holes 36B are at a medium radius and are used when the hammer tips begin to wear some, while holes 36C are set at the longest radius from shaft 32 and are used when the hammer tips are worn nearly to their limit of usefulness.

The holes 36A, 35B and 36C of the adjacent spaced parallel discs 34 are aligned from disc to disc so that the long anchoring pins 38 may be driven through all of the discs and when in place the pins 38 are thus parallel to the axis of the shaft 32. The spacing of the discs is sufficient to permit the pivot end of the hammers, generally designated A, B and C herein, to be placed between the discs. In Figure 1 the hammers shown are of type C, hereinafter more fully described. It is to be understood that in this specification the mill illustrated in Figure 1, per se, forms no part of the present invention and that the invention is in the particular type of hammer which is used in themill.

Referring to Figures 2 through 4 there is illustrated one form of the improved removable tip hammer of the present invention. The hammer consists of a main body portion 40 which has a thickness T, Figure 3, sufficient that it occupies, except for a clearance, the space between successive discs 34 of the mill. The main body portion is provided with an aperture 4| of a size such that it will pivot neatly upon the pivot pins 38 of the mill when the hammer assembly is in place thereon.

Referring to Figure 2 the main body portion 40 of the hammer extends outwardly from the hole 4| and terminates in a dove tail portion generally designated 42, the dove tail portion being defined by the line 44 which extends transversely across the hammer to and then around the smoothly rounded curve portion 45 and thence outwardly to the smoothly rounded curve portion 46, thence again transversely along the line 4! and around the smoothly rounded curve portions 48 and 49 and thence outwardly along a transverse line 50 which is in the same plane as the line 44. The surface defined by the line 44-50 may thus be defined as generated by moving a line parallel to the axis of the pivot hole 4| (which is also parallel to the axis of pivot pin 38 and to the axis of rotation of the shaft 32) along the line 4450 which defines the dove tail end of the main body portion.

The removable extremely hard and tough hammer tip portion generally designated 5| has a cast-in recess of the same shape as the dove tail on the portion 48 except that slight clearance is allowed in the dimensions so that the hammer tip 5| may be slid parallel to the axis of hole 4| for placement of the hammer tip on the main body portion 40 of the hammer and also for removal. The tongue portions 52 and 54 of the hammer tip 5| thus are seated within the smoothly rounded curve portion 45 and 49 of the main body part 48 of the hammer, and the hammer tip is therefore held firmly against outward movement in the direction of arrow 56 when the mill is in operation.

Movement of the hammer tip 5| parallel to the axis or hole 4|, which would permit the head 64 of a bolt 65 is seated in a somewhat protected position. Similarly, plate 59, which is shown'in Figure 5,'is provided with a recess at 66 to receive the nut 68 into which the bolt 65-is screwed for clamping the plates 58 and 59 in place" in assembled relation, as shown in Figure 3. Thus, in fitting the parts of the hammer assembly together the tip is first moved in a direction parallel to the axis of the hole 4| so as-to bring the two tongues 52 and 54 into engagement with the dove tail end of the main body portion 40 of the hammer. Then the plates 58 and 59 are mounted in the recesses 60 and GI, respectively, and they are in turn held in place by the bolt 65 which isinserted through the: aperture 69 of plate 58 which continues as the aperture I through the main body portion andthence continues as aperture II in plate 59,-the bolt 55 being then turned up firmly intothe;nut.68 'which is held from rotation due to the configuration of the recess 66 in the retaining plate 59. Above the-aperture 69-'I|ll| there isa smaller aperture 'I3I4'I5 formed in part inthe plate 58, the main body portion 40 and the-plate 59, respectively. This smaller aperture is located so that when the cotter pin I6 is inserted therethrough the enlarged loop head ll of the cotter pin will lie against one of the fiat surfaces of the head 64 of bolt 65 and thus prevent it from turning. The opposite end of the cotter pin is bent over, as indicated at I8, Figure 3 ..Referring to. Figures 6,, 7 and 8 there is illustrated aslightly modified form of the invention, namely type B which is the same as type A of Figures 3 through except that the hammer tip is provided with internal recesses 89 and 8| extending downwardly from the recesses 60 and SI vwhich, as explained with reference to type A, is formed in part in the main body portion 40 andthe hammer head 5|. The retaining plates 58 and 59 of type B, Figures 6-8, are likewise provided with downwardl extending portions 82 and 83, respectively, which fit into the recesses 80 and 8| when the plates are rotated from the dotted line positions shown in Figure 7 to the full line positions. The portions 82 and 93 which are the outward ends of the plates 58 andv 59, respectively, when the hammer is working, are thus held in the recesses 80 and 8|, respectively, and this makes for less possibility of displacement of the retaining plate during operation. The bolt 65; Figures'G-B, thus has only to hold the inner' (upper) ends of the plates 58 and 59.

. Referring to Figures 9-11 there is illustrated a further modified form of the invention, herein known as type C. In this modification of the invention the main body portion 90 of the hammer is, as before, provided with an aperture 9| through-which the mounting pins 38 are inserted for attaching thehammer assembly to the rotor of the mill. The main body portion is likewise provided with a clove tail end shaped along the 6 i lin94, 95,96,91, 98, 99,100, but in this instance the dove tail end is not shortened in a transverse direction, but, on the contrary, is -somewhat thicker than the dimension TI at the mounting end of the hammer assembly, Figure 10, it'being' noted that the hammer body portion in the direction parallel to the axis of hole 9| is formed with curved surfaces at IOI and I02 terminating in thesurfaces I93 and I04 which are spaced apartby the distance T2 (Figure 10) which is also the head width of the hammer. The hammertipl05 has a side view shape the same as tha't shown for types A and B, being provided with arecess of dove tail shape at I06 cor-' responding to the'dove tail end 94-400 of the mainbody portion 99 of the hammer. The assembly of the hammer tip I05 to the main body portion is; as with types A and B, accomplished by'sliding the hammer parallel to the axis of hole 9| until the hammer tip is aligned, as shown in'Figure 10. Across'th'e end of the dove tail jointlormed in the main body portion 99 and the hammer tip I and on each of the faces I93'and 'IM of the hammer assembly, there are provided recesses. Thus, recess I08 is provided in the face I03 and recess I09 in face I94. Each of these recesses overlaps the dove tail end of the'main body portion 9|] and the hammer tip andthe recesses are of sufficient depth to receive the'head I I0 and nut III of the retaining bolt II'2 whichpasses through a hole II4 that is formed in the boundary of the dovetail portion 94I00 of the main bodyportion and the cor-'- responding dove tail portion I05 of the hammer tip I95. Adjacent the hole I I4 there is a smaller hole H5 through which the cotter pin IIIi ex tends. 'When the cotter pin is in place and crimped over, the head H8 is held fiat against one or the fiatsides of head III! of bolt H2 and thus prevents it from turning. Similarly, the crimped e'nd IIS of the cotter pin prevents the nut ||I from turning. If desired, the aperture I09 may be made smaller so as to fit the configuration of the nut I II leavingonlyi a small space in which the cotter pin II9 may be crimped down. When so formed the cotter pin need serve only to hold the head III) .of the bolt from turning rather than both the head, andthe nut thereof.

It may be noted that in each of the three styles of hammer assemblies previously described, the hammer andhammer tip are symmetrical about a central plane passing lengthwise through the hammer assembly and through the axis of the pivot ,of the hammer. Being so constructed the hammer tip of any of the modifications may be reversed with respect, to the hammer body without removing the latter so as to present a new breaking' surface. This is illustrated in Figures 12 through 17 which also show the manner in which the hammer assembly may be set radially outward in successive steps so as to utilize all or mostof the material in-the hammer tip. In this group of figures the lines 36A, 36B and 36C represent the path of movement of the holes 36A, 36B and 36C' of Figure 1. Thus, the line 36A which represents hole 36A of Figure 1, is the shortest radius while line 3613 represents the medium radius and. 360 represents the longest radius. InFigures 12 through 17 the particular style of hammer gillustrated is that shown in Figures 9 through'll, but-it is to be understood'that Figures 12 through 17 are equally representative of the manner of use of the style of hammer assassin:

assemblies; shown in Figures, 3' through 5 and 6 throu h. 8.

,When the hammer tip is new it has a rectangular: configuration of: its outer end, as shown, in; Figure 12. During initial use the hammer is mounted on its pivot pin. which is then placed in hole 36A, thus rotatingthe hammer at the shortest radius (from the centerof shaft 32). This; is possible since at this time the hammer tip has its maximum dimension. As the hammer tip grinds material, its striking surface finally wears to the shape shown by the dotted line a-b, which is the first stage of wearing; The mill is. then shut down and the hammer tip N is reversed to the position shown in Figure 1-3- which then brings the line ab to the rear edge of the. hammer away from the striking surface. At this change the hammer: mounting pins remain in, holes 38A. The mill is then again put into operation and the striking surface of the hammertips then wears away until the tips assume the configuration shown by the line c-d a. This is the second stage of wearing.

The mill is then again shut down and the pivot pins 38 are removed and the entire hammer assemblies and the pins 38 are set down to the medium radius hole at position 36B. This has the effect of bringing the entire hammer to a longer radius with reference to shaft 32 and brings the hammer tip closer' to the grid 20. This position is shown in Figure 14. The mill is again put in service and the hammer tips during operation wear away to the dotted line e-f which is the third stage of wearing. The mill is then taken out of service, the bolts H2, holding the hammer tips in place, are removed and the hammer tips are reversed, which has the effect ofpositioning the hammer tips as shown in Figure 115.. The mill is then again put in service and gradually wears the hammer tips to the dimension shownby the dotted line g--hwhich is the fourth stage ofwearing, at which time the mill is; again taken out of service and the pins 38 are removed and the hammers are set out to the longest radius hole 360. This new positioning is. illustrated in Figure 16. When the mill isagain put in service the hammer tips again wear, thistime to the dimension shown by the dotted line i-7 which is the fifth stage of wearing, whereupon. the. mill is. again shut. down, the bolts H2, are-removed and the hammer tips are-reversed .to the position shown in, Figure 17. and uponagain being put in service, the tip wears, to the dimension shown, by the dotted line k-Z, which is regarded as the final stage of usefulness. The pins 38 and all the hammers are then removedjthe bolts, H2 are loosened from each of. the. hammers and each hammer is then provided with. a new replaceable tip of full dimension, and the hammers are reassembled to the shortest radius hole 36A, as .in Figure 12.

In, Figures 12 through 17 the original dimensions of the hammer tips are shown in, dotted lines for purposes of illustrating the amount of material which is worn away during service life of the hammer tip. It will be appreciated that by this manner of construction the hammer tip is given an exceedingly long, useful life and that the out-of-service time of the mill required for reversing or setting out the hammers is reduced to a. minimum. It may be noted parenthetically that some operators reclaim the hammer tips by welding-on additional material by the electric arc welding process, although this frequently" gives bad results due to theiact that it introduces, variations in the length and width of the hammer; tips, thus upsetting proper operation of the-mill;

As many apparently widely different embodl, ments of this invention may be made without de;-.

parting from the spirit and scope thereof, it is to be understood that I do not limit myself to; the specific embodiments herein except as defined by the appended claims.

What I claim is:

1. A hammer comprising a main body portion. formed with an opening adjacent one end there! of, a dove tail portion formed at the opposite. end of the main body portion, a hammer tip pore.v tion formed with a pair of forwardly facingtongues with curved ends, said tongues received. inmating engagement with said dove tail portion, rectangular depressions formed in either side of the body portion and the hammer tip portion and overlapping the tongues and dove tail portion, plate like retaining means fitting the depressions. in the body portion and the hammer tip portion, fastening means passing through aligned holes; in the retaining plates and the body portion, and the portion of the retaining plate adjacent the fastening means being of lesser thickness than the remaining portion for protecting the ends of the fastening means from wear.

2. A hammer comprising a main body portion formed with an opening adjacent one end thereof, a dove tail portion formed at the opposite end of the main body portion, a hammer tip portion formed with a pair of forwardly facing tongues with curved ends, said tongues received in mating engagementwith said dove tail por tion, rectangular depressions formed in either side of the body portion and the hammer tip, portion and overlapping, the tongues and dove. tail portion, plate like retainingmeans fitting the depressions in the body portion and the hammer tip portion, fastening means passing through aligned holes in the retaining plates and the body: portion, and the portion of the retaining plate adjacent the fastening means being of lesser thickness than the remaining portion for protecting the ends of the fastening means from wear. said hammer tip portion formed with internal; recesses at either side thereof adjacent the rec tangular depressions, and said retaining plates, formed with downwardly extending portions re-. ceivable within said internal recesses.

FRANK J. LOU-EEK.

REFERENCES CITED The following references are of record in the, file of this patent:

UNITED STATES PATENTS Number Name Date Re. 14,865 Plaisted May 25,, 1921! 590,748 Williams et a1 Sept. 28,1897; 1,212,991 Newhouse Jan. 16, 1 917 1,940,116 Brooks Dec. 19, 19.33, 2,045,688. Armstrong June 30, 1936 2,186,047 Stine Jan. 9, 19.40 2,397,776 Clark Apr. 2, 1946 2,467,865 Smith Apr. 19, 1949 FOREIGN PATENTS Number Country Date 17,858 Great Britain Aug. 3, 1901 554,677 Germany July 9, 1932 

